SharePoint does not function like a typical web server. Instead of HTML pages, SharePoint utilizes Active Server Pages (.aspx) by default. These types of pages are created in a SharePoint site as Basic and/or Web Part Pages.
Basic Pages and Web Part Pages are pieces of content created and stored in SharePoint document libraries. Although relatively straightforward, this concept takes a while to get used to. Because nearly all SharePoint data is stored in a SQL database, this is the method the SharePoint developers chose for displaying this type of content. So, in a nutshell, if you need to add a simple basic web page to a SharePoint site, you will need to add it to an existing document library and then link to it as necessary.
The first step in understanding how these components work is to create some Basic Pages and Web Part Pages yourself. To create a Basic Page in a SharePoint site, follow the technique outlined here:
The page will then be displayed with the formatted text you entered, a top menu bar, and a link for editing the content.
The page itself will be visible in the contents of the document library. You can create a link to the page from anywhere else in the portal, and it will link directly to the page you want. For example, a link to a Basic Page may look something like this: